Production of gasoline by thermal cracking, catalytic cracking and reforming



2,981,674 CATALYTIC April 25, 1961 G. M. GOOD PRODUCTION OF GASOLINE BY THERMAL CRACKING,

CRACKING AND REFORMING 2 Sheets-Sheet 1 Filed 001.. 24, 1955 HYDRO- ESULFURIZATIONI J SYSTEM l Y m MM l Wm UM RT T A S ES HWY RY CE .W m R l 1 l I l I I l I IIV l I I I II G l I I I 1 I l I I ltlrllllulllllal g M MG 7 w J TNM 2 4 Y 7 5 Mm q. m TA R 6 G MC 2 C B H M r 3 B Run 5 O EC 2 3 C KO 1 H M R A J D 0 ME H O m CF U r r w N Rl l. RA U. P. man s f R. Emmm OCE E MIE W .R W 6 K 2 N l EM MCD m. HR 0 FEE R C 6 E F A L E l D T U B m l D BLENDING INVENTORZ GEORGE M. GOOD QMZJ un HIS ATTORNEY FIG! April 1961 G. M. GOOD 2,981,674

PRODUCTION OF GASOLINE BY THERMAL CRACKING, CATALYTIC CRACKING AND REFORMING Filed Oct. 24, 1955 2 Sheets-Sheet 2 CAT. CRACKED GASOLINE SEPARATOR STRIPPED r" PRODUCTS I REGEN. FLUE GAS I TRIPPER L CAT. CRACKED l 1 A02 PRODUCTS los * 4 REACTOR I l l 1 X3? qrzr sro THEMAL l GASOLINE AIR INVENTOR:

GEORGE M. GOOD the invention is'to provide an improved "fcrackin'g the remainder. I

V dehydrogenation catalyst. i I

- In another embodiment of the invention the catalytic 2,981,674 PRonUCrIoNoF GASOLINE BY THERMAL CRACKING, CATALYTIC CRACKING AND REFORMlNG I v I I.

George M. Good, Port Chester, N.Y., a ss ignor to fSh ell OilCompany, acorporation Delaware Filed Oct. 24, 1955, Ser. No. 542,151 I i 4 Claims. crane-70 I This invention relates to the production of high octane gasoline from hydrocarbon oils of low value, particularly residues and similar materials which are poor feedstocks for catalytic cracking.

The object of the invention is to provide a new and useful process'whereby materials which arepoor feed stocks for catalytic cracking may be converted to a large N extent to high quality gasoline and valuable olefins in a practical and advantageous manner. Another objectsof process forthe upgrading of thermal gasoline.

The process of the invention in its broader aspect comprises thermally cracking the hydrocarbon oil under conditions to produce an olefinic thermally cracked gasoline, catalytically cracking the thermally cracked gasoline .under conditions of such severity that the olefins are substantially completely cracked to lower boilingproducts which are removed, and catalytically reforming the thermally and catalytically cracked gasoline.

In a preferred embodiment of the invention the thermally cracked gasoline is catalytically cracked with a finely divided cracking catalyst at a temperature .above,.-

900 F. under conditions wherein substantially the entire contact of the gasoline vapors withthe catalyst is effected while the, catalyst is carried concurrently in dilute suspension in thevapors.

In a preferred embodiment of the invention the cata lytic cracking operation is carried out under special conditions in conjunction with a normal catalytic cracking operation as will be more fully described.

. In another preferred embodiment the thermally cracked gasoline is separated from unconverted oil, it any, and .1,

I then topped to remove the lower boiling material up through about the C3 hydrocarbons prior to ,catalytically In still another embodiment of'the invention the catalytic hydroforming operation is carried out on the catalytically cracked gasoline without prior desulfurization using the fluidized catalyst technique and a finely divided hydroforming is preceded by a catalytic desu lfurization treatment and is carried out under severe conditions using asupported platinum catalyst. II 4 I I In general, it is the desire of refiners to process as much as possible of the-available heavy oils by catalytic cracking. However, certainmaterials are known to be very poor feed stocks for catalytic cracking either because they contain contaminating materials which are harmful to the cracking catalyst or because they produce excessive amounts of coke in the process. In general, all residue stocks, i.e., stocks containing material which cannot be distilled in'conventional refinery equipment, belong to this class. Certain distillate stocks such as coker cycle stock and some catalytic cracking cycle stocks are also poor feed stocks for catalytic cracking.

The handling of these materials presents a difficult Various attempts have therefore been made to Patented Apr. 25, 1961 re 1C problem. Insomecases they may be blended into fuel oil or asphalt or, burned to produce carbon black. In

fmost cases, however, it is thepractice to convert them at least in part to. gasoline and other distillable products by therrnally 'cracking them. Thermal cracking, as the term is here used, denotes any process wherein an oil or residue is subjected to high temperatures inthe range above 8005 F. fora time sufiicient to, crack an appreciableportion of the material into gas and hydrocarbons boiling in the gasoline boiling range. miliar Dubbs cracking process and its modifications, the thermal reforming of. naphthas, and also coking (either delayed or fluid) and viscosity breaking are thermal cracking processes. The essential feature is that the splitting is ,induced non-catalytically. by heat alone.

The amount; of gasoline produced in these various thermal cracking processes I depends largely upon the characterqof the feed and upon the cracking conditions. In some cases thermal cracking is not carriedout under conditions to produce the largest amount II of. gasoline possible but under modified conditions (because of coking problems or, the like) to produce substantial amounts of light, oils and/ or gas. The gasoline produced in such thermal cracking processes is normally high insulfur and invariablycontains considerable amounts of unsaturated ..compounds of both olefinic and diolefinic nature.

At one time the thermal gasoline was considered a de-' sirable component suitable for use in even best grades of gasoline. At present, however, it unsuited for use in the better grades of gasoline except when blended in small amounts with other premium grade materials. upgrade thermal gasoline. l i I I It is known .that thermally cracked gasoline may be upgraded to, a certain extent by treating it with a cracking 7 catalyst under special conditions- Although a cracking catalyst is used in this case the conditions are purposely held so mild that cracking is substantially avoided. The

upgrading is not through cracking but is effected primarily through isomerization of the olefins present and dehydrogenation of the naphthenes byhydrogentransferwith the isomerized olefins. The catalysts commonly used for catalytic cracking are, known to readily effect these isomeri zing and hydrogen. transfer reactions. Thus, by this treatment thelolefins irrthe thermal gasoline are largely saturated and th e naph therie s are dehydrogenated to aromaticsu ,This latteureaction leads to a substantial improvement in the octane number. Howeven the saturation of part of the ole-fins-leads to a substantial reduction in the octane nuinber and the net gain is'therefore rather small. This gainis not sufiicient to make the process k economical and consequently it is not .used.

It is known that thermal gasoline maybe upgraded With a better net gain in octane-number by catalytic reforming, i.e., by-treating; it in the presence of a catalyst I .having.hydrogenation dehydrogenation activity under con- -ditions of temperature and pressure where the thermodynamic equilibrium between naphthenes and aromatic I .ing In, hydrbfor ining dehydrogenation of the naph other ji'eactions such as. isomerijzation, hydrogenation, cyclization, andhydrocracking take place to,app'reci-' favors the aromatics. The catalytic, reforming is best; carried out under pressure in the presence ofadded hydrogen inwhichcasethe operationis called hydroform thenes iis the octane number-raising reaction but ab le extents a n d arealso of much importance, .particularly in the case of parafiinic stocks. This process, as applied to thermally cracked gasoline, has, however, sev- .eral disadvantagesforfshortcomings which greatlyj mili fate against usa e. .In the first place, it is found that thermal gasoline'w hen hydrofor med generally causes exe ar i nai t pa e 1 I Thus, e it hl in Thus, the fastrongly' favor the dehydrogenation of-naphthenes, they are strongly favorable to saturation of the olefins. Consequently, the olefins are completely hydrogenated at an extremely rapid rate with a large localized liberation of 'heat due to the exothermic nature of the reaction. Thirdly, the hydrogenation of the olefins, even if these are first isomerized, leads to a substantial reduction in the octane number which limits the net gain to a value which is much less than would otherwise be obtained. Hydroforming is only economical in its usual application when isufiicient hydrogen is producedto-allow withdrawing at least a bleed stream in order to maintain the purity of the recycled hydrogen-containing gas at a satisfactory level. When 'hydroforming thermally cracked stocks, however, there is generally a large hydrogen consumption. For this reason, if for no other, thermally cracked stocks cannot be economically upgraded by hydroforming except when treated in small amounts along with the normal hydroforming feeds. At present, most of the catalytic hydroforming operations are carried out under relatively severe conditions using a supported platinum vcatalyst. Thermally cracked gasoline would generally not be upgraded in this case without first subjecting it to a catalytic desulfurization treatment which, incidentally, greatly reduces its octane'number by saturation of the olefins.

In spite of the mentioned disadvantages and shortcomings, thermal cracking followed by catalytic hydroform- 'ing is the most attractive method hitherto available for the production of gasoline of suitable high octane number from such stocks which cannot be profitably cracked catalytically. Thus, the most satisfactory method in the past has been to thermally crack the feed, separate the thermal gasoline, and then either hydroform it in small amounts along with a straight run hydroforming stock or subject it to a hydrogenating desulfurization treatment followed by catalytic hydroforming.

Most of these disadvantages are avoided in the process of the present invention. The hydrogen consumption is low and in fact there is generally a substantial net hydrogen production; the degrading elfect of saturation of the 1 olefins is avoided; the stock may be separately hydroformed rather than having to treat it in admixture with a large amount of straight-run material; also considerable amounts of C and C olefins are'produced which may be polymerized or alkylated-in the known manner to produce additional amounts of premium components which may further improve finished gasoline.

The process of the invention will be described in connection with typicalexamples and with relation to the the quality andyield of the accompanying drawings of which: I a Figure I is a flow diagram wherein the processing operations are indicated by labeled blocks. The small blocks labeled F represent vfractionation facilities. ,The

process illustrated in Figure I includes the preparation 1.is passed to the crude fractionation and catalytic crackingfeed stock preparation. unit 2 and is separated therein into the usual products including distillate feed for catalytic cracking 'which'is passed by line 3 to the catalytic cracking. system 4, and a residue or pitch which is passed by line 5 to the thermal cracking system 6.

In the caseillustrated the feed stock to the thermal V cracking unit '6'is a straight-run residue,"e.g.,-from a "oline had the following ASTM distillation:

vacuum flashing operation. Actually the feed stock may be any hydrocarbon oil but more particularly, an oil which is not amenable to catalytic cracking and more particularly a residue material. In the particular example, which will be described, the oil feed was a catalytic cracking cycle oil. 7

In the thermal cracking system the feed is subjected to thermal cracking conditions to produce thermally cracked gasoline along with other higher boiling distillable material. The product is passed by line 6a and separated in F-7 into gas which is passed by line 7a to the gas recovery system, an 'olefinic thermally cracked gasoline which is withdrawn by line 8, heavier distillates which are withdrawn by line 9 and a residueof pitch or coke which is withdrawn by line 10. The end point of the gasoline may be in the usual range of from about 300 to 400 F. but is preferably on the high side and may. be as high as about 450 F. In the particular example the thermal cracking of'the mentioned feed was carried out in a Dubbs cracking unit under approximately the following conditions:

Heater pressure p.s.i 600 Transfer temperature F 950 Reactor pressure p.s.i 300 Reactor temperature F 900 Flash pressure p.s.i 125 Combined recycle ratio 1.9

The product yields were as follows:

I Percent v. Unstabilized cracked gasoline 49.5 Cracked residue (5 API) 48.7 Stripper gas oil 1.0 Loss 0.8

In the particular example the debutanized thermal gas- The thermally cracked gasoline, or at-least a rnajorpart thereof containing the C hydrocarbons, is passed by line 11 and/ or 11a to the catalytic cracking system. The

. material may be catalytically cracked by itself in a separate system as was indeed the case for the particular example, but it will ordinarily be uneconomical to do so for several reasons. In the preferred embodiment of the invention it is separately catalyticallycracked in a side reactor coupled to a conventional catalytic cracking unit as be more fully described in connection with Figure In a specific embodiment of the invention the thermally cracked gasoline from line 8 is not passed by line 11 to the catalytic cracking system, but to F-12 wherein it is topped by first removing light material boiling up through approximately the C hydrocarbons which material is removed by line 13 and can be blended with the finalv product. The topped gasoline is then passed by line 11a to the catalytic cracking system.

In the particular example the mentioned thermally cracked gasoline was re-run to remove lower boiling material' up through C and asmall amount of the heavy ends. The gasoline then had the following composition:

: Percent v. Saturates 39.5 Olefins 46.1 Aromatics 14.4

and an F-l octane number with 3 cc. TEL of 72.4.

"The thermal gasoline is eatalytically cracked'in such a "properly upgrade it. i "The severity of the catalytic cracking conditions is pmmanner that the catalytically cracked gasoline produced from the thermal gasoline maybe separately recovered.

The catalytic cracking may, in other respects, becarried out with any of the known cracking catalysts and by any of the known operating techniques. A preferred catalyst is a silica-alumina cracking catalyst such as widely and/ or dehydrogenate the naphthenes by hydrogen transfer but is carried out under sufficiently severe conditions that the unsaturated compounds in the gasoline are largely and preferably substantially completely cracked to lower boiling products. Some naphthenes and paraflins may also be cracked under these conditions but the corn ditions are preferably controlled to minimize the crackaction in the subsequent catalytic reforming.) If the cracking conditions are too mild the gasoline is not materially improved" in the subsequent catalytic reforming.

On the other hand, if the conditions are toosevere the] gasoline is likewise not amenable to a sizeable iinprovement by subsequent catalytic reforming and requires a 'more costly low pressure catalytic reforming treatment to a ing of these hydrocarbon types. (The dehydrogenation of naphthenes is an important octane number-raising remarily a function of the cracking temperature, the partial pressure of the feedfvapor, and the space velocity and can be adjusted in the known manner by control of one or more of these variables. Ordinarily in catalytic cracking the severity of thecracking conditions is measured in teams of the conversion which is often defined as 100 minus the recovered liquid product boiling above the gasoline boiling range (usually a cut point of 450 F.).

Since the feed in the present case normally contains little if any material boiling above 450 F. the conversion cannot be defined in this way. Since the catalytic cracking when carried out in the preferred manner, as will be later described, effects primarily the cracking of the unsaturated material in the thermally cracked gasoline, the preferred upper limit of conversion is expressed in terms of this reaction. As thus considered the severity is preferably held below that giving a residual olefin content as measured by F.I.A. Analysis (ASTM designation D1319,54T) of less than about 5%.-This measure of severity is, however, not applicable to define the lim ts in the mild direction since under very mild conditions the unsaturation may be removed by hydrogenation transfer which is here not desired. The conditions are mamwhile the applicable conditions are only limited by the condition that the olefins in the thermally cracked gaso line are to a large extent but not completely cracked, the preferred upper or lower limits of the catalytic cracking severity may be defined as described. Actually, there is no upper limit to the severity of the catalytic cracking conditions in the broader aspect of the invention since what may be called overcracking simply requires a more severe catalytic reforming treatment to reach the same product quality level. This is not desired but is permissible. In the particular example being described the mentioned thermally cracked gasolinewas catalytically crackedin a fixed bed fluidized catalytic cracking ope-.1.

6 tion with the above described cracking catalyst under the following conditions;

Weight hourly space velocity 2. 0 3. 7 Temperature, 0 500 550 Process period, min. 15 7. 5 Pressure, atm 1 1 The yields in weight percent were as follows:

Below 0 15.9 I 20.1 Liquid Product 8:2. 9 78. 7 Coke .4 1.2 1.1

As pointed out above, the F 1 octane number with 3 cc. TEL of the topped thermal gasoline (Le. the feed to the catalytic cracking step) was 72.4.. The F-l octane .number with 3 cc. TEL of the product of Example B topped in the same manner. was 74.0. It will be noted that the, octane numberof the material is not appreciably improved. The purpose of the operation is here notto improve the gasoline as such but to improve it for subsequent reforming. a f l The product from the catalytic cracking operation issuing by line 14. is s eparated in F-15 into a lower boiling product which is passed to thegas recovery system 16 by line 17 and a. liquid product 'which is passed by line 13 to the catalytic reforming system All of the C material may be passed to the catalytic reforming operaden, or P415 may be operated to remove, the gasoline tops whichare'suitable for blending without further'reforming. In such case the tops, are passed by line 20 to blending and the re-run gasoline is passed to the reforming system. Bottoms may be removed by line 18a. The end point of the re-run gasoline feed to the reforming may be chosen such that the reformed product doesnot repuire re-running, e.g., 390 F., or it may be chosen some- What higher (especially when using a regenerative reforming process) and the product then re-run to give the desired end point. a

, 'In the case of the particular example being illustrated, the above-mentioned gasolines were re-run as indicated above before reforming them.

The catalytic reforming may be efi'ected using anyof the known hydrogenation-dehydrogenation,type reforming catalysts and may be carried-out in any of the various Ways known to be suitable for catalytic reforming in general. It may be carried out either with or without hydrogen. In this process, however, there is a particular advantage in employing the fluidized catalyst technique and recycling hydrogen in the reforming step such, for instance, as is the casein the known Fluid Hydroforming Process (see Oil and Gas Journal, May 17, 1954, ppf122- 12.4). In this case the catalyst which is used in the f orm a of a powder normally comprises as the predominating hydrogenatiomdehydrogeriation promoter oxides of one or more metals from the group consisting ofjCr, Mo, W, Co, Ni, Ru, Rh, Pd, Re, and Pt in combination with a suitable support of diluent which may be, by way of example, alumina, magnesia, silica, silica-alumina, silicamagnesia, titania, silica-zirconia, zinc spinel, preferably in micro-porous form. The catalyst may or may not also contain promoters such as one or more halogens, e.g., combined fluorine. The operation may be carried out at pressures from about .1 to about atmospheres with hydrogen-to-hydrocarbon. feed ratios from about 2 to about 20 molar and at temperatures from about 800 F. to about 1100 F. These variables are correlated inlthe known manner such that under the prevailing conditions of partial pressure of hydrogen and temperature the abovedescri'oed equilibrium fayors the formation of arc esses. in the vapor phase with a nickel-molybdenum or cobaltcry of the product.

cracking of the thermal gasoline'is effected while the :7 matics in the process. e space velocity may then be adjusted to strike the desired compromise between yield and gain in octane number. The material may be reformed along With other conventional reforming stocks,

e.g., the conventional straight-run naphtha, but there is bed of catalysts having platinum as the'predominating hydrogenation-dehydrogenation promoter. In this case, it

is generally necessary to desulfurize the gasoline to a 1 sulfur content below 0.05% prior to reforming it. This may be done using any of the known desulfurizing proc- One suitable process is to hydrogenate the feed molybdenum catalyst under temperature and pressure conditions conducive to hydrogenation e.g., 550750 F. and 5-50 atmospheres. Product gas from the subsequent reforming operation may be used to supply the hydrogen. Thus, in this case, the material from line 18 does not pass directly to the reforming system, but by line 21 to the desulfurization unit 22 and then by line 23 to the reforming unit.

A'suitable catalyst for the catalytic reforming consists of a small amount of platinum e.g., 0.1-1% supported on a halogen-promoted alumina e.g., 0.1-3% chlorine and/or fluorine or a silica-alumina composite. The operation is preferably carried out at temperatures between about 825 and 975 F., pressures between about 5 and 50 atmospheres with a hydrogen-to-hydrocarbon mole ratio above about one. In the specific example being illustrated, the mentioned gasolines after the catalytic cracking operations were catalytically reformed under the following conditions:

Catalyst UOP R-S Platforming catalyst Temperature, C. 498 Pressure, p.s.i.g 700 LHSV 3.0 H /feed mole ratio 6.0

The yields and octane numbers of the products were as follows:

' When catalytically hydroforming the same topped thermally cracked gasoline (without the catalytic cracking operation) under the same hydroforming conditions (temperatures 496 and 509 C.) the Fl-0 octane number at 92.0% volume yield was 69.2 and at an F-l-O octane number of 77.8, the volume yield was 88.1%.

.The product from the catalytic reforming treatment 7 is then sent to blending by line 24, thereby completing the process. 1

As pointed out above, in a preferred arrangement in the invention, the catalytic cracking of the thermal gasoline is carried out in a special manner in combination with a conventional catalytic cracking operation. The catalytic cracking of the conventional catalytic cracking feed stock, e.g., gas oil may be effected in any of the conventional ways and a side stream from the catalyst regenerator may be used to' effect the catalytic cracking of the thermal gasoline in a separate reactor affording separate recov- In the preferred arrangement, the

catalyst is carried inthe gasoline vapors, at relatively high velocity, e.g., 10-60 ft. per second, through a tube to a separator. It is of particular' advantage when catalytically cracking the thermalgasoline to effect the cracking in this way, rather than with a fluidized bed of catalyst. In order to prevent the catalyst from collecting in a fluidized bed the cracking is carried out in a long tubular reactor of sufficiently uniform diameter that a suitably high velocity is' maintained .in all parts. This type of operation combined in an advantageous manner with the catalytic cracking of a conventional catalytic cracking feed stock is illustrated in Figure II.

Referring to Figure II, the apparatus comprises a catalyst regenerator catalytic cracking reactor of 101; two catalyst strippers 102 and 103; and a reaction tube separated catalyst passes by line 107 to vessel 102, wherein it is stripped with vapors passed up from vessel 103. The stripped products are removed overhead as shown and the catalyst flows by line 108 to the reactor 101 where it is used to catalytically crack a conventional feed stock such as gas oilintroduced at the bottom as. indicated.

The overhead vapors from reactor 101 are passed to .a

recovery-system (not shown) where it is separated into gas, catalytically cracked gasoline, and heavier oils.

Catalyst from the. catalytic cracking reactor 101 passes by line 109 to the bottom of a riser. line wherein it is picked up by steam, as indicated, and carried into the stripper 103. Additional stripping steam is introduced into the bottom of this vessel as indicated. The steam plus stripped products then pass up through the stripper 102. The stripped catalyst passes by line 110 to the bot tom of a riser where it is picked up by air and carried back into the regenerator, thereby completing the catalyst cycle.

In the system illustrated the hot regenerated catalyst is first used to catalytically crack the thermal gasoline at a high temperature e.g., 1000 F. It is then stripped with steam and then used to catalytically crack a conventional 'feed stock. After this, it is again stripped and then recycled to the regenerator. V

The tie-in of the above-described catalytic cracking operation is further illustrated in the flow diagram of Figure I wherein F25 is the conventional catalytic cracking main fractionator receiving product from the main catalytic cracking reactor (i.e., 101 of Figure I) by line 26 inFigure I. The gaseous products up to about C 7 are passed by line 27 to the gas recovery system; the

gasoline is passed by line 28 to blending; the heavier material is recycled in part by lines 29 and30 and passed in part by line 29 to the thermal cracking system;

I claim as my invention: r

1. A process for the production of gasoline from heavy hydrocarbon oil which comprises subjecting a heavy hydrocarbon oil tothermal cracking under conditions to produce an olefinic thermally cracked gasoline, separating from the thermally cracked gasoline thus produced the lower boiling part up through about C hydrocarbons, catalytically cracking the remainder of the thermally cracked gasoline by itself at a temperature above 900 F. and at a severity to-crackmost of the olefins to lower boiling products, separating said lower boiling products and subjecting the remainder to a catalytic reforming treatment with a dehydrogenation catalyst.

2. Process for. the production of gasoline according to claim 1 further characterized in that the thermally cracked. gasoline is catalytically cracked with a finely divided cracking catalyst at'a temperature above 900 F. with substantially theentire-contact ofthe gasoline-with the catalyst being effected while the catalyst is carried concurrently in dilute suspension in the gasoline vapors.

3. Process for the production of gasoline according to claim 1 further characterized in that the thermally and catalytically cracked gasoline is catalytically reformed without prior desulfurization by a hydroforming treatment with a finely divided supported molybdenum oxide catalyst.

4. Process for the production of gasoline which comprises subjecting a hydrocarbon oil to thermal cracking under conditions to produce an olefinic thermally cracked gasoline, separating from the thermally cracked gasoline the lower boiling part up through about the C hydrocarbons, catalytically cracking the remainder of the thermally cracked gasoline by itself at a temperature above 900 F. and at a severity such that the cracked products boiling below C are upward of 30% by weight of the olefin content of the thermally cracked gasoline, separating from the product thus produced the lower boiling part up through about C, hydrocarbons, subjecting 10 the remainder to a catalytic reforming treatment with a dehydrogenation catalyst, and blending with the product the above said lower boiling part of the thermally cracked gasoline.

References Cited in the file of this. patent UNITED STATES PATENTS 2,253,486 Belchetz Aug. 19, 1941 2,382,910 Pinkston Aug. 14, 1945 2,430,096 Barcus Nov. 4, 1947 2,448,553- Schutte et al. Sept. 7, 1948 2,451,041 Murphree Oct. 12, 1948 2,529,790 Waddill Nov. 14, 1950 2,644,785 Harding et al. July 7, 1953 2,678,263 Glazier May 11, 1954 2,684,325 Deanesly July 20, 1954 2,773,810 Kimberlin et al Dec. 11, 1956 2,895,899 Kunreuther et a1 July 21, 1959 

1. A PROCESS FOR THE PRODUCTION OF GASOLINE FROM HEAVY HYDROCARBON OIL WHICH COMPRISES SUBJECTING A HEAVY HYDROCARBON OIL TO THERMAL CRACKING UNDER CONDITIONS TO PRODUCE AN OLEFINIC THERMALLY CRACKED GASOLINE, SEPARATING FROM THE THERMALLY CRACKED GASOLINE THUS PRODUCED THE LOWER BOILING PART UP THROUGH ABOUT C6 HYDROCARBONS, CATALYTICALLY CRACKING THE REMAINDER OF THE THERMALLY CRACKED GASOLINE BY ITSELF AT A TEMPERATURE ABOVE 900* F. AND AT A SEVERITY TO CRACK MOST OF THE OLEFINS TO LOWER BOILING PRODUCTS, SEPARATING SAID LOWER BOILING PRODUCTS AND SUBJECTING THE REMAINDER TO A CATALYTIC REFORMING TREATMENT WITH A DEHYDROGENATION CATALYST. 